1. Field of the Invention
The embodiments described herein relate generally to tomographic systems, such as computed tomography (CT) systems, and, more particularly, to CT systems that scan a continuous stream of objects, such as luggage, for explosive or contraband detection.
2. Description of the Related Art
At least some known explosive detection systems use tomographic systems to scan a continuous stream of objects. In such tomographic systems, it is generally necessary to partition data generated by the tomographic system into blocks associated with each object in the stream of objects. For such tomographic systems to perform partitioning of the data successfully, the tomographic system determines an extent of each object and completes data acquisition for each object as each object passes through the tomographic system. As used herein, the term “extent of an object” refers to the physical boundaries, dimensions, and/or measurements of the object, such as the physical volume of the object, and/or data representing the physical object. In at least one known explosive detection system, a machine control for a scanning device generally receives information, such as an identification tag, about each object from an external system that transports the objects into a scanning device, such as a CT system. At least one CT system includes passive curtains to shield an external environment from X-ray radiation produced by the CT system. However, objects passing through the passive curtains may be repositioned, such as by moving adjacent each other or shifting orientation, before and/or inside the scanning device. Such repositioning may cause confusion between the extent of an object as externally measured, and the extent and position of the object once inside the scanning device. As such, there is a need to determine extents of objects within the scanning device.
In at least some known tomographic systems for scanning a stream of objects, the acquisition system, which captures scan data of an examination area, identifies a leading edge and a trailing edge of an object using an internal light sensor array. However, such a light sensor array may provide a rapid determination of a leading edge and a trailing edge of an object, but may lack accuracy and may fail to properly determine a leading edge and a trailing edge of irregularly shaped objects. As such, there is a need to quickly and accurately determine the physical extents of objects.